yeah i have been on sleepingtrains website.. emailed them a few times without reply.. was just wondering whether it was as (bearing in mind july/august) time that trains would fill up, because of peak times.

I think it is not always possible, to just show up and get the ticket u want, at the train station. Last time I bought a train ticket, in Cairo, they only had third class tickets, for the next train going. Luckily I am not fussy. But that was 10 years ago. Maybe things have changed.

When I went to Egypt, I just got someone at the hostel I was staying at to book everything for me the day I turned up and within a couple of days which was the day I wanted to travel, I was on the overnight/sleeper train from Cairo to Aswan (goes via Luxor). So if my experience was anything to go by you should be fine just booking when you arrive in Cairo, maybe don't leave it until the day o departure just to save you some worries.